Arylalkyl and aryloxyalkyl phosphonates as antiviral agents

This application is a division of application Ser. No. 912,502, filed June 5, 1978.

(a) Field of the Invention

The invention relates to arylalkyl- and aryloxyalkylphosphonates, to the preparation thereof, and to compositions and methods for the use thereof as antiviral agents.

(b) Description of the Prior Art

J. C. Collins U.S. Pat. No. 3,917,718, issued Nov. 4, 1975, discloses compounds useful as pesticidal and antiviral agents and having the formula ##STR1## wherein Ar is phenyl or substituted phenyl, Alk is alkylene of 6-10 carbon atoms, and R is lower-alkyl. The compounds are prepared by reacting an arylalkyl halide, Ar--Alk--X, where X is bromine or iodine with an alkali metal salt of a diketone having the formula H 2 C(COR) 2 .

J. C. Collins and G. D. Diana U.S. Pat. No. 4,031,246, issued June 21, 1977, discloses compounds useful as pesticidal and antiviral agents and having the formula ##STR2## wherein Ar is phenyl or substituted phenyl, Alk is alkylene of 3-10 carbon atoms and R is lower-alkyl. The compounds are prepared by reacting an aryloxyalkyl halide, Ar--O--Alk--X, where X is bromine or iodine with an alkali metal salt of a diketone of the formula H 2 C(COR) 2 .

Sodium phosphonoacetate, (HO) 2 P(O)CH 2 COONa, has shown antiviral activity against herpes infections in test animals; cf. S Baron and G. Galasso, Chapter on Antiviral Agents, page 166, Annual Reports in Medicinal Chemistry, Vol. 10 (1975).

W. J. Linn and R. E. Bensen, J. Am. Chem. Soc. 87, 3657-72 (1965), at page 3671 disclose the compound diethyl (4-methylbenzyl)phosphonate, 4-CH 3 C 6 H 4 CH 2 P(O)(OC 2 H 5 ) 2 , as a chemical intermediate.

In a composition of matter aspect, the invention relates to compounds having the formula ##STR3## wherein Ar is phenyl or phenyl substituted by one or two substituents selected from the group consisting of halogen, lower-alkoxy of 1 to 4 carbon atoms, hydroxy, alkanoyloxy of 1-4 carbon atoms, carbo-lower-alkoxy of 2-4 carbon atoms, carbamyl and carboxy;

Y is (CH 2 ) n or O(CH 2 ) n wherein n is an integer from 6 to 8; and R is alkyl of 1-6 carbon atoms.

In a further composition of matter aspect, the invention relates to compounds having the formula ##STR4## wherein Ar is phenyl or phenyl substituted by one or two substituents selected from the group consisting of halogen, lower-alkoxy of 1 to 4 carbon atoms, hydroxy, alkanoyloxy of 1-4 carbon atoms, carbo-lower-alkoxy of 2-4 carbon atoms, carbamyl and carboxy;

Y is (CH 2 ) m or O(CH 2 ) m where m is an integer from 3 to 10;

R is alkyl of 1-6 carbon atoms;

and

R' is alkanoyl or carboalkoxy of from 2 to 4 carbon atoms.

In a further composition of matter aspect, the invention relates to a composition for combatting viruses which comprises an antivirally effective amount of a compound of Formula I or II in admixture with a suitable carrier or diluent.

In a process aspect, the invention relates to a process for preparing a compound of Formula I which comprises heating a compound having the formula Ar--Y--X, where X is bromine or iodine, with a compound having the formula P(OR) 3 or an alkali metal salt of a compound having the formula HP(O)(OR) 2 .

In a further process aspect, the invention relates to a process for preparing a compound of Formula II which comprises heating a compound having the formula Ar--Y--X, where X is bromine or iodine, with an alkali metal salt of a compound having the formula R'CH 2 --P(O)(OR) 2 .

In a further process aspect, the invention relates to a method of combatting viruses which comprises contacting the locus of said viruses with an antivirally effective amount of at least one compound of Formula I or II.

The compounds of Formula I are prepared by either of two alternative methods, both starting from a common intermediate halide having the formula Ar--Y--X.

In the first method, the arylalkyl or aryloxyalkyl halide is heated with a trialkyl phosphite, P(OR) 3 , preferably at a temperature between about 150° and 200° C. The relatively volatile alkyl halide, RX, is formed and distilled out of the reaction mixture leaving behind the product of Formula I which can be purified by distillation at reduced pressure or chromatographic procedures.

In the second method, the arylalkyl or aryloxyalkyl halide is heated with the alkali metal salt of a dialkyl phosphonate, HP(O)(OR) 2 , said alkali metal salt being prepared in situ from the phosphonate and an alkali metal, preferably sodium or potassium, in an inert organic solvent prior to addition of the halide. The reaction occurs readily at a temperature between about 50° and 100° C., conveniently at the reflux temperature of the inert solvent, for example, hexane or tetrahydrofuran. In the event the arylalkyl halide or aryloxyalkyl halide is a bromide, the reaction can be catalyzed by the addition of a trace of iodine or sodium iodide.

The intermediate arylalkyl halides and aryloxyalkyl halides Ar--Y--X, are a known class of compounds, described in Collins U.S. Pat. No. 3,917,718 and Collins and Diana U.S. Pat. No. 4,031,246, respectively.

The compounds of Formula II are prepared by a process analogous to the second method for preparing the compounds of Formula I, that is, by reacting an arylalkyl halide or aryloxyalkyl halide, Ar--Y--X, with a compound having the formula R'CH 2 P(O)(OR) 2 in the presence of a strong base, such as an alkali metal, e.g. lithium, sodium or potassium, or a strong base derived therefrom, e.g. a hydride or amide, which forms the alkali metal salt of the phosphonate involving the active methylene group (CH 2 ) intervening between the carbonyl function (R') and the phosphorus atom. The reaction takes place in an inert organic solvent at a temperature between room temperature and about 100° C.

The compounds of formulas I and II where Ar is substituted by carbamyl or carboxy are preferably prepared by reacting the corresponding compounds when Ar is substituted by carbo-lower-alkoxy with ammonia or with an alkaline hydrolysis medium, respectively; although it is possible to effect the functional group conversion prior to the phosphonate alkylation process if desired.

The structures of the compounds of the invention were established by the modes of synthesis, by elementary analysis, and by infrared and nuclear magnetic resonance spectral determinations.

Biological evaluation of the compounds of the invention has shown that they possess antiviral activity. They are thus useful in combatting viruses present on inanimate surfaces as well as viral infections in animal organisms. The in vitro testing of the compounds of the invention against herpes simplex viruses types 1 and 2 and various RNA viruses has showed that they inhibited viral growth at minimum concentrations (MIC) ranging from about 0.4 to about 25 micrograms per milliliter. The MIC values were determined by standard serial dilution procedures. In vivo activity has also been demonstrated in the treatment of mouse genital herpes simplex type 2 infection, and guinea pig herpetic skin infection.

The antiviral compositions are formulated by preparing a dilute solution or suspension in an organic or aqueous-organic medium, for example ethyl alcohol, acetone, dimethyl sulfoxide, and the like; and are applied to the locus to be disinfected by conventional means such as spraying, swabbing or immersing. Alternatively, the compounds can be formulated as ointments or creams by incorporating them in conventional ointment or cream bases, such as alkylpolyether alcohols, cetyl alcohol, stearyl alcohol and the like; as jellies by incorporating them in conventional jelly bases such as glycerin and tragacanth; or as aerosol sprays or foams. The antivirally effective component of the composition is present in a concentration of between about 0.7 parts per million and about 5 percent by weight, depending upon the chemical species used, the object to be treated and the type of formulation employed. For disinfection of inanimate surfaces with aqueous or aqueous-organic solutions, concentrations in the lower part of the range are effective. For topical application in medical or veterinary use in the form of ointment, cream, jelly or aerosol, concentrations in the upper part of the range are preferred.

The following examples will further illustrate the invention without the latter being limited thereby.